1. Field of the Invention
The present invention relates to a microrelay which is a micromachine used as, for example, a mechanical switch and an actuator.
2. Description of the Related Art
With reference to FIGS. 11 through 13, a conventional microrelay will be described.
The conventional microrelay shown in FIG. 11 includes a substrate 500 having two sets of fixed contacts 510a and 510b fixed thereon (only one set of the fixed contacts 510a and 510b are shown in FIG. 11) and a movable section 600 having two movable contacts 621L and 621R corresponding to the fixed contacts 510a and 510b. The substrate 500 has a top surface and a bottom surface, each of which has two grooves 520L and 520R. A covered conductive wire 530 is provided in the grooves 520L to be wound around the substrate 500, and another covered conductive wire 530 is provided in the grooves 520R to be wound around the substrate 500, thereby forming electromagnetic coils 550L and 550R each acting as a magnetic force generating device.
The movable section 600 includes a frame 610 and a movable body 620 coupled to the frame 610 through a coupling section 630. The movable body 620 has magnetic bodies 622L and 622R in addition to the movable contacts 621L and 621R. When one of the two electromagnetic coils 550L and 550R is excited, the movable body 620 is pivoted as a seesaw about the coupling section 630 as a pivoting axis, thereby contacting one of the movable contacts 621L and 621R which corresponds to the excited electromagnetic coil on the corresponding fixed contact 510a or 510b (FIG. 12). In this manner, the fixed contact and the movable contact in contact with each other become conductive to each other.
The above-mentioned conventional microrelay has the following problems.
For example, when the coil 550L is excited, a magnetic flux is transmitted through the magnetic body 622L and also through the other magnetic body 622R (FIG. 13). Accordingly, the movable body 620 is not actually pivoted about the coupling section 630 as an axis, but is entirely attracted to the substrate 500. Since the pressure load applied on the fixed contact 510a by the movable contact 621L is insufficient in this state, the utilization factor of the magnetic flux is low. Such inconveniences prevent the microrelay from being produced compactly. Further, when the magnetic body 622R is attracted to the substrate 500, and thus the movable contact 621R approaches the fixed contact 510b, high frequency signals are transmitted between the movable contact 621R and the fixed contact 510b, resulting in a decline in the signal blocking capability of the microrelay.